Method of forming contacts



Feb. 17, 1931. H. o. SIEGMUND y METHOD oF FORMING CONTACTS Filed Nov. 27, 1928 II/ /IJ /NVE/.V 70H BVH. 0. .Slee/vulva Y J @In mdp( A T TORNEY its supporting member; and

riUMriinnYs o. 'sinon/Urin or` wnsir ORANGE, NEWJERSEY, 'ass'rdnon frojnnLL PHONE manometromns,A inoonionarnn OENEW venir, noonrons'rron or NEW YORK METHoroor romaine ooiirnor's Appiicarion inea November 27, `1s2a1seriai Nanszazi'i.

This invention relates to contacts for electrical switching apparatus and more particularly to a bi-metallic Contact having a base of contact metal, such asplatinum, of the .proper .thickness to give the required Contact life, and a backing of base metal, to give the material the necessary thickness to provide adequatespacing between Contact springs. K

Tn accordance with this invention, a biinetalliccontactV is formed by uniting con tact metal to base metal as a foundation, the Contact metal being so formed as to overlap the base metal to facilitate the formation of apron on the sides of the base metal to prevent smutting of the contact metal from sidevsparking. These contacts are preferably produced by soldering with silver solder or other suitable soldering alloy an ingot of contact metal tocan ingot of base metal and rolling the resulting bi-inetallic block down to the required dimension in a manner to produce indentations at right angles to cach other in the base metal from which the contacts vmay be cut and welded to their supporting members after which the apron may be formed around the base metal.

ln the drawings Fig. 1 is a view of a bimetallic ingot made of precious and base inetal before the rolling operation;

Fig. 2 is a view of the bi-metallie ingot after the rolling operation;

Fig. 3 is a view of the bi-metallic `plate 'showing indeiitations formed in the base niet al Fig. 4 isan example of a tool suitable for use for the forming of the indentations shown in the plate of Fig. 3;

Fig. 5 is a view of a tape of Contacts slit from the plate shown in Fig. 3;

Fig. G is a view of a contact slit from the tape shown in Fig. 5 ready for welding on Fig. 7 is a cross-sectional view of the c ontact after the apron forming operation, showing the forming tool for efecting such operation in position thereon.

ln the construction of the contacts of this invention the ingot 10 of precious or contact metal shown in Fig. 1, is united as by welding or 'otherwise to thebase metal block ll after. which the bil-metallic bloclrthus formed may be rolled down in any well-known inanner to forni a bi-nietallic sheet as shown in Fig. 2 of tiie required thickness. This bimetallic sheet or plate may then be put on an ordinary press fitted'with the Vforming tool T shown in Fig. 4, for forming the indentations 1Q andv 13 in the base metal at right l In this formingtool .z

angles to each other. the thickness of the walls 21 determine the width of grooves 12 and 13 and tlie size of the cavities 22 which-in turn determine the size of the metallic blocks llafter the forming operation.

The tool T is preferably provided with parallel ridges Vor'knife blades 14; adapted for slitting the precious metal 'sheet simultaneously with the forming of the indentations. longitudinal aXis of grooves 12 as indicated bythe dotted lines 15 shown in Fig. 3, thus obtaining a tape of contacts as shown in Fig. 5. This tape may in turn be slit transversely along the dotted lines 16 to produce contact blanks as shown in Fig. 6. These contact blanks are then secured to suitable supporting members or springs 20 as shown in Fig. 7 as by welding.V The precious metal which overlaps the base metal'may then be bent downwardly in order to forni on all sides of the base metal block 11 a sparking protecting apron. Y Y n lt is obvious that by the use of proper forming tools the effective or contacting poi'- tion of the precious inetalmay be given'a fia-t surface as shown in Fig. 7 or any other desired configuration, depending upon the type of electrical apparatus to which these contacts may form a part.

What is claimed is:

1. The method of making Contact elements comprisinguniting an ingot of contact metal tacts to springs and forming the same so that These blades are disposed along the an apron of Contact metal partially covers the sides of the base metal.

2. The method of making Contact elements comprising uniting an ingoi'J of Contact metal o to an ingot of base metal, rolling the resulting loi-metallic block to the required clmensions and forming recesses-at right angles to each other in the base metal, slit-ting the precious metal into tape, cutting Aoontzmts lo therefrom 'and attaching the contacts to springs and forming the same so that an apron of Contact metal partially covers the sides of the base metal.

In Witness whereof, I hereunto subscribe l5 my naine this 23d day of November, 1928.

HUMPHREYS O. SIEGMUND. 

